1. Field of the Invention
This invention relates to a cartridge detachably mountable to an electrophotographic image forming apparatus employing electrophotography, such as a laser beam printer or a copying machine. Here, the electrophotographic image forming apparatus is one that forms images on a recording medium by using an electrophotographic image forming system. Then, as examples of the electrophotographic image forming apparatus, it includes, e.g., electrophotographic copying machines, electrophotographic printers (e.g., laser beam printers and LED printers), facsimile machines, and word processors. Incidentally, a process cartridge is one in which a charging means, a developing means or a cleaning means and an electrophotographic photosensitive member are integrally joined in a cartridge and this cartridge is set detachably mountable to the main body of the electrophotographic image forming apparatus.
2. Related Background Art
In conventional electrophotographic image forming apparatus making use of electrophotographic image forming processes, a process cartridge system is employed in which an electrophotographic photosensitive drum (hereinafter “photosensitive drum”) and process means acting on the photosensitive drum are integrally joined in a cartridge and this cartridge is set detachably mountable to the main body of the electrophotographic image forming apparatus. In such a process cartridge system, a system is available in which, e.g., the photosensitive drum and at least one of a charging means, a developing means and a cleaning means or at least the developing means are integrally joined in a cartridge and this cartridge is set to be detachably mountable to the main body of the electrophotographic image forming apparatus.
According to the process cartridge system of this type, the apparatus can remarkably be improved in operability because its maintenance service can be performed by users themselves without relying on servicemen. Accordingly, this process cartridge system is widely used in the electrophotographic image forming apparatus.
The process cartridge is, to describe it with reference to FIGS. 15 and 16, commonly constituted of three frame members: a cleaning frame member 113, which integrally supports a photosensitive drum 107, a charging roller (not shown) and a cleaning blade (not shown); a developing frame member (not shown) which integrally supports a developing roller (not shown) and a developing blade (not shown); and a developer holding frame member (hereinafter “toner frame member”) 111, which holds therein a toner. It is also constituted of side covers 190 and 191, which cover drive gear trains (not shown) at the sidewalls of the developing frame member and the toner frame member or either of them.
As means for fastening the above frame members and other component parts, commonly used are screws, heat caulking, resin joining (fastening by injection of molten resin) and so forth. Besides, as means for fastening component parts, employed are joining techniques, such as hot-melt bonding and ultrasonic welding (see, e.g., Japanese Patent Application Laid-open No. H10-20744).
However, such conventional joining techniques have had the following problems.
The cleaning frame member 113 is commonly provided with a cutout 101 in order that a photosensitive drum unit D integrally having a drum flange 136 and the photosensitive drum 107, the former receiving a driving force from the main body of an electrophotographic image forming apparatus, can readily be assembled to the cleaning frame member. As the result, there arises a problem that its periphery has a low rigidity. In some cases, it has been necessary to reinforce it with a rib. Where a drum bearing 138 is fastened with screws X to such a cleaning frame member, the area of a joint at which the cleaning frame member 113 and the drum bearing 138 are joined is defined substantially only by the screw's bearing surface (region d). Hence, the effect of enhancing the rigidity of the cleaning frame member may become poor also after the drum bearing 138 has been joined thereto. Moreover, in joining with screws, the joint position is limited in relation to space. In practice, the drum bearing 138 is often joined at a place separate from the part where the shaft of the drum unit D is received. In addition, since the joint area is also small as stated above, the positioning precision of the drum unit D tends to be low. There also have been such problems.
In order to improve the rigidity or improve the positioning precision, it is ideal that the drum bearing and the cleaning frame member are widely joined and also joined around the shaft of the photosensitive drum in an annular shape (or arc shape) after the shape of the shaft and that the drum bearing and the cleaning frame member stand integrated. However, where it is attempted to make the drum bearing and the cleaning frame member integrated by joining them both widely and around the shaft of the photosensitive drum in an annular shape (or arc shape) according to the conventional methods, e.g., by the resin joining (by injection of molten resin) or by injecting a hot melt, an adhesive or the like, there has been a problem that the peripheries of joints tend to deform under heat and pressure because, in injecting the molten resin or in injecting the hot melt, the joints must be heated to a high temperature at the time of injection in order to melt the material to be injected, or a high pressure is required in order to inject a highly viscous material. Also, in order to keep the peripheries of joints from deforming, there has also been a case in which a large-size jig holding the drum bearing and the cleaning frame member is provided. Incidentally, the improvement of the rigidity and the improvement of the positioning precision are likewise required also when the developing frame member, the toner frame member or the side cover are joined.
A case in which the frame members (and component parts) are joined using a material different from materials for them, such as hot melts, adhesives or the like, is undesirable because such a case is disadvantageous in regard to the recycling of materials after cartridges having been used are collected and there is a possibility of causing a lowering of quality such as a lowering of mechanical physical properties and flame retardance of recycled materials (regenerated materials).
Reference is made below in regard to terpene compounds.
As known in the art, compounds of a terpene type are the principal components of essential oils obtained chiefly by steam distillation of vegetables and are commonly used as perfumes.
Meanwhile, the terpene compounds are also known to have uses other than the above. For example, d-limonene, which is a monoterpene, has a molecular structure very similar to that of styrene, and has the property of dissolving polystyrene even at normal temperature. Hence, as disclosed in Japanese Patent Application Laid-open No. H5-263065, it is used as a shrinking agent for foamed styrol.
Besides, as disclosed in Japanese Patent Application Laid-open No. 2002-20703, a technique is proposed in which the surface of a joining resin is dissolved with an additive containing limonene, and is further heated in a dissolved state to agitate the joining resin surface, in the state of which the joining resin is fused to what is intended.